The invention relates to a process for feeding metal to a molten metal bath, in particular for the purpose of melting down solid metal such as for example scrap metal or granular dross, and relates also to a device for accomplishing same.
With a view to protecting the environment, and in recognition of the limited availability of raw materials, increasing efforts are being made to recycle raw materials. This includes metal which appears in large amounts in industrial and household waste and applies in particular to the recycling of used cans as metal cans are being employed increasingly today as containers for drinks of various kinds.
One possibility for recycling is to introduce the scrap metal into a molten metal bath in order to melt it down. In that case it is particularly important for the solid metal to be immersed as quickly as possible in a turbulent metal stream in order to minimize oxidation of the metal and to increase the efficiency of melting. Counterproductive in this respect is that thin walled metal such as in scrap cans is much less dense than the melt; as a result, the scrap metal tends to remain on the melt surface for a long time. This is unfavorable in view of the above mentioned efforts to minimize metal oxidation and to increase melting efficiency.
On the other hand processes exist in which the melt is made to rotate in a container so that a whirlpool is formed near the middle of the melt, and the metal to be melted is introduced into the whirlpool. In practice it has been found that the metal still tends to stay on the surface of the melt, also in the whirlpool. Furthermore, the turbulence produced at the surface of the melt and at the place where the scrap is introduced into the container creates an excessive amount of dross. Also, the heat transfer from the melt to the metal is small and the resultant efficiency of melting is unsatisfactory.
The object of the present invention is therefore to develop a process and device of the above mentioned kind by means of which metal which is to be melted sinks as fast as possible below the surface of the melt and is therefore excluded from contact with air as quickly as possible. The process and the device are, furthermore, intended to be useable in many different ways and in particular should enable better mixing-in of alloying additions made to the melt. Also, it should be possible to melt down granular dross to achieve a high metal yield without the use of salts.